Headers vs stock exhaust manifolds. Opinions?

I have been running a set of TTI headers on my 383 for about 15 years now and aside from being ceramic re-coated twice they are still in great shape. The mechanic who is doing my engine install really wants me to switch back to stock HP manifolds for all the reason we know, they burn the wires, they get in the way of lots of stuff and generally take up too much room. He found some stock HP manifolds on Year One for about $650 (I had no idea they were being reproduced)and was asking me if i wanted to put them on in place of the headers. He feels that the stock HP manifolds will flow almost as good as the long tube headers. He is doing some massaging on the tubes to give more clearance for the wires and switching some of the 90 degrees plug ends to straight boots so help as well.




I am going to stay with the existing TTI headers myself, but thought i would get some input on this from you all if they stock manifolds are worth the extra hassle for any HP gains?


Thanks
Stu

I switched from Hooker Super Comp to HP exhaust manifolds.I see very little difference at low rpms. When I get on it you can feel a difference up top, not much but its there. Depends on your build. Im running the MP .528 mechanical which is ideal with manifolds. To me the ease of starter removal, no burnt wires and no maintenance out weighs the Headers headaches. $650 is too much for repo manifolds. You can get originals for
$400 or less.

There are a lot of good reasons to run manifolds, but to say they flow "almost as good" as your TTIs is simply not true.

I would use what you have. They fit the modified theme anyway.

That was my impression as well that they flow way better then stock, so much so it's worth the small hassles.

Plus, he's got it wrong that flow is the main issue. Separation of the exhaust pulses is the more important function of headers. That's why, in a well designed test, headers increase torque below the torque peak as well as above. A well designed tunnel ram has the same advantages, just on the other side of the flow path.

Some of the four cylinders in the last half of last century used a cast iron manifold that went from 4 to 2 and then it was tubes until the collecter. The 4-2-1 header. This is really successful in a 4-banger or a V8 with a 180 degree "flat" crank. It's also the reason that circle track headers often have a tube or two swapping between the banks.

R.

I have over 10,000 miles on my TTI 2" pipes. I have never burned a plug wire and have not burned out or worn out a starter. If you build it right, the plug wires, starter and everything else will not be a problem.
It cracks me up these guys that tout the advantages of stock exhaust manifolds.
I see guys at car shows blab about how the engine needs backpressure to run right.
If you never go past 1/3 throttle or over 2800 rpms, the manifolds are probably just fine.
The only advantage I see with manifolds is fitment. They fall short in every other category.

Since it is not a daily driver, don't have to worry about rust out, re using the existing headers is probably what I would recommend.
I would put a new quality starter on it while it is apart tho.

I was watching a you tube vid the other day, they had a reasonably built hemi on the dyno, they swapped the headers for a set of exhaust manifolds, now bearing in mind that hemi exhaust manifolds are pretty exceptional pieces in themselves, the hemi dropped 65 HP, food for thought !

The mechanic is wrong.

I went from manifolds to Dougs headers on my small block and picked up 70+ hp.

Car went from a best of 14.2 to 13.0

I had a great local shop build a 340 stroker motor for me but I wanted stock carb and manifolds as it's going in an OE restoration. He broke the engine in using his favorite Holley carb and headers. After break-in the final numbers were 397 HP-465 TQ. After he swapped over to stock exhaust manifolds and thermoquad the final numbers were 395HP-443 TQ

What cam and heads are you running? That will really dictate how much those headers are benefiting you. If your cam and heads are pretty tame, the headers may not be better enough to really justify them. I mean, you have them already so I wouldn't change them because coated TTI headers aren't exactly the same as the summit cheapo junkies, so yeah.

Yea, i am keeping the TTIs but was just wondering about how much the gain in HP is worth the hassles of headers after we started discussing it.

In fact thinking back I can't remember a car i owned that didn't have headers on it except for a daily driver.

Stu

Might be a few exceptions!!

I am willing to bet that you were using stock heads on this build and the reason your hp didn't change is because your heads are the biggest cork in engine. if you swapped heads to Edelbrocks or something similar and the redo the test you would see a very large difference between headers and manifolds. Stroker motors can push a lot of air at a lower RPM but you quickly find the limit of flow in the heads.

On a mild 383 with a fairly small cam, the difference is probably only like 20hp.

I've dyno tested several stroker FAST builds, and I can tell you the volumetric efficiency of those motors is really quite low, especially for the level of effort involved with the builds.

I'd say that most of the ones I tested would have easily made 100hp more with headers, and maybe a cam swap........ But probably 50-70hp from the headers alone.

How much difference you'd see depends on what you're testing.

I'm just going to go weep in the corner!! Stupid rules!!!! A conserative 50 hp! "The sound of someone softly weeping"

On a stock 383 with a good exhaust system I would guess 20HP gain with the headers as well. I have swapped headers onto stock engines and not felt much gain. On a built 440 with street ported heads and camshaft you would see more of a gain. IMHO.

Headers all the way.

There is something about the sound of headers that is just right for a musclecar. Stock Cast iron manifolds don't cut it and sound kinda boring and anemic.

I would argue that the rest of the exhaust system has more to do with the exhaust note than the minor difference between headers or cast iron manifolds. Usually most if not all of the exhaust system is changed when making a swap from exhaust manifolds to headers or vice versa so there's no apples to apples comparison.

The SuperCar and FAST cars running stock manifolds with free flowing exhaust systems sound anything but boring and anemic.

Welcome to Moparts.... You'll fit right in.

http://www.hotrod.com/articles/mopp-0106-manifolds-vs-headers/

I went by an article on a 360 with headers and... it was utter garbage.

My mild 5.9 in my Duster with NO OTHER changes went from 14.2 to 13.49 out of the box and with jetting changes dropped to 13.0.

Manifolds vs headers - headers beat manifolds like a rented car.

In the last Mopar Muscle and Hemmings Muscle Machines they each did a stock type build and then added headers. The 340 in MM made 320 hp and with headers it made 352 hp. With the 6pk on it the eng made 356 hp and like 376 hp with headers.

Hemmings tested a 426 Hemi and made 494 hp and with headers it made 521 hp. As for me I will take the headers anyday. I have been running my TTI's for 6 years now with no leaks at all and never a burnt plug wire. I will take the headers as I like to race my car sometimes so why not go for the extra hp. Manifolds are fine if you dont plan to race or run a class where you have to run them. Ron

https://www.youtube.com/watch?v=nBed8HkXlow

Did you read the article?

It basically says the same thing, but with dyno numbers

Yup and the numbers are fairly low, I found the spread to be much wider.

What a timely post, just last night I took manifolds off a Hemi and installed headers. That driver's side manifold looks incredibly restrictive. No comparison on ease of installation, but I believe the swap will be something akin to 'pulling a cork' out of the exhaust system.

The TTI headers with Schumacher mounts fit like a glove by the way.

I'll bet on a mild 383 you'll gain almost as much just by using 2 1/2" 440 head pipes (instead of 2 1/4" 383 pipes) as you would going to headers. 440's had H pipes which helped a bit too, you'll need to section an RB head pipe set to narrow it to use on a B motor.

Factory motors all had wide 114-ish lobe spreads which reduces overlap, generally the narrower the lobe separation (tighter, ie 106-110) angle the more headers help you. headers are also somewhat limited by the rest of the exhaust system too.

I had a basically stock 69 440 out of a Newport with ported closed chamber 67 "915 heads and a 484 purple shaft in a 73 duster with narrowed factory "Newport" logs on both sides. I realized on the Pass side I could fit a 68-71 Magnum Ram horn manifold so I did, The car picked up about 1 1/2 tenths (IN THE 1/8TH!) so maybe 2 1/2 in the 1/4? So it does help, but I'll bet if I ran the wider LSA 528 the gains would not have been as significant.

I've read that on small blocks a set of ported Magnums are about as good as Shorties and better than ported 340 manifolds